Since a hydrosilylation curable silicone composition typically has poor adhesion to metals and organic resins, especially to base materials of thermoplastic resins or the like, the following proposals have been made, for example. A curable silicone composition comprising: an organopolysiloxane having an alkenyl group bonded to a silicon atom; an organohydrogenpolysiloxane having a silicon atom-bonded hydrogen atom; an adhesion promoter containing an isocyanuric acid derivative having at least one type of functional group selected from the group consisting of epoxy groups, glycidoxy groups, and alkoxysilyl groups, and at least one type of group selected from the group consisting of crosslinkable vinyl groups and hydrosilyl groups (Si—H groups); and a catalyst for hydrosilylation reaction has been proposed (see Patent Document 1). A curable silicone composition comprising: an organopolysiloxane having at least two alkenyl groups in a molecule; an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms in a molecule; an isocyanuric ring-containing organosiloxane having an allyl group, an epoxy group, and an organosiloxy group in a molecule; and a catalyst for hydrosilylation reaction has been proposed (see Patent Document 2). A curable silicone composition comprising: an organopolysiloxane having an alkenyl group bonded to a silicon atom; an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom; an adhesion promoter consisting of an isocyanuric acid derivative having an alkoxysilyl group and/or an epoxy group, and a divalent siloxy unit-containing group, and a silane or siloxane compound having an alkoxy group and/or an epoxy group, but having no isocyanuric ring; and a catalyst for hydrosilylation reaction has been proposed (Patent Document 3).
However, there has been a problem in that adhesion to base materials that are in contact even with these curable silicone compositions during curing is not sufficient.